Integrated circuits having numerous semiconductor devices commonly are formed on semiconductor chips that are then mounted in integrated circuit packages having multiple pins. An electro-static discharge to one or more of the pins of an integrated circuit package can force a pulse of current into a semiconductor device in the integrated circuit. The absorption of this energy can damage or destroy the semiconductor device particularly a sensitive device such as a MOS device which has thin gate oxides.
Electro-static discharge (ESD) circuits are often formed with and connected to semiconductor devices in order to protect the devices. An ESD circuit may be connected to vulnerable pins of a semiconductor device and would operate to absorb energy from an electro-static discharge in order to avoid damage to or destruction of the semiconductor device.
A problem that may occur with ESD circuits is damage to the ESD circuit itself after absorption of several electro-static discharges. As a result of electro-static discharge that may occur, ESD circuits may leak current because of damage internal to the ESD circuit. For example, p-n junctions in the ESD circuit may leak significant amounts of current after absorbing current pulses from numerous electro-static discharges.